This invention relates generally to the cleaning of laboratory glassware and more particularly to apparatus for drying laboratory volumetric flasks and other long necked glassware articles.
Beakers, flasks, test tubes and other glassware which is commonly used in laboratories must be thoroughly cleaned after use in order to remove deposits which could contaminate materials subsequently contained in the glassware. Often, glassware is cleaned manually with a brush. This manual procedure is generally unsatisfactory because it requires considerable time on the part of highly paid laboratory assistants or other personnel whose time can be spent more productively on other tasks. Also, the detergent is very difficult to rinse from the glassware, usually requiring an acid rinse.
The automatic glassware washing machines that have been available in the past operate much like ordinary household dishwashing machines. The glassware is inverted and loaded on one or more racks which can be moved into and out of the cabinet of the machine. One or more spray arms located beneath the rack or racks apply upwardly directed wash and rinse sprays which wash and then rinse the glassware. Heated air for drying of the glassware is circulated within the cabinet during the drying cycle.
Although this type of machine effectively cleans and dries beakers and other glassware articles having a wide mouth, volumetric flasks and other narrow necked glassware articles are not thoroughly washed by conventional spray arms. The long, narrow neck of the flask prevents the wash and rinse sprays from fully entering the flask and effectively cleaning and rinsing its inside surface. In order to enter the flask at all, the spray must originate directly beneath the open end of the flask. Even then, the long neck usually intercepts the spray before it reaches the body of the flask. Consequently, the inside of the flask is not adequately washed, particularly the bottom surface which is most in need of washing because it is most likely to contain wax, grease, chemicals and other residues.
Thorough drying of long necked flasks is even more difficult. Circulating hot air within the washer compartment is not effective because the circulating air cannot enter and flow through the narrow neck of the flask in sufficient quantities to adequately dry the inside of the flask. Hot air drying dries the outside flask surface and raises its temperature above that of the inside surface which is less exposed to the circulating air. The air within the flask remains moist, and water particles condense on the cooler inside surface of the flask when it is removed from the machine, even though the flask appears to be dry. Condensation creates water spots and build up of water within the flask. Consequently, even if the flasks are thoroughly washed and rinsed, the machines that have been used in the past are not able to effectively dry flasks and other narrow necked articles of glassware.